My microwave GE model # JVM1440WH04 spacemaker has no heat coming out of it. My husband heated microwave lasagna in it last, everything works except for the heat, any solutions?

Push the microwave door tightly closed. The computer will not start cooking until the door is closed for safety reasons. Some models of microwave will give a warning on the screen if the door is open.
2

Ensure you have programmed a heat setting, entered a cooking time and pressed the "Start" button on the microwave's keypad. Check that the microwave is not set to "Defrost" mode.
3

Unplug the microwave and wait for one minute. This measure will reset the microwave's internal computer if it has frozen or scrambled. Plug the microwave back in and try again.
4

Ensure the keypad lock mode is inactive. Most microwave ovens have a lockout feature that prevents children from starting the microwave while unsupervised. Lockout mode is usually deactivated by holding down the button that bears a padlock symbol